Coating method and apparatus for notches and other surface discontinuities



Feb. 11, 1964 ow COATING METHOD AND APPARATUS FOR NOTCHES AND OTHER SURFACE DISCQNTINUITIES Filed May 31, 1960 INVENTOR. Rober/ Law BY Buck/70m, Chem/7am, 8 B/ore ATTORNEYS United States Patent CUA'HNG METHQD AND APPARATUS FGR NOTm3 OTHER SURFACE DES- CQNTHJUIIIES Robert Low, Beaverton, Greg, assign'or to Tektronix, Inc, Portland, Greg, a corporation of Oregon Filed May 31, 1960, Ser. No. 32,879 Claims. (Cl. 117-95) This invention relates to a coating method and apparatus and more particularl to a method of applying a coatmg liquid to a selected portion of the surface of an article especially to dificultly accessible surfaces, such as the interior surfaces of notches in notched members in a rapid and efiicient manner and to an apparatus for carrying out the steps of such method.

The method and apparatus specifically disclosed in this application is particularly adapted for applying a silver paint, also referred to as ceramic silver, to the interior of notches in the edges of ceramic plates as a step in producing terminal mounts employed in precision electrical apparatus. Such silver paint is a commercially available product and is a suspension of finely divided silver in an organic vehicle including a binder and a solvent. It is a viscous liquid which readily adheres to ceramic surfaces and dries to an adhesive film by evaporation of the solvent. The ceramic terminal mounts referred to are produced in large numbers and consist of relatively thin glazed ceramic strips or plates having notches in the edges thereof, which notches may, for eX- ample, be of rectangular conformation having a width of to %2 inch and a depth of two or three times their Width, the ceramic members being, for example, to %s inch thick.

The notches in the finished terminal mounts have their interior surfaces covered With a laminated coating including a thin layer of silver provided by firing the plates after the interior surfaces of the notches have been coated With the silver paint referred to and the coating dried. Such laminated coating also includes an outer layer of soft solder applied after the fired plates have been cooled by dippin the notched edges of the plates in soft solder to provide a layer of such solder on the surfaces of the silver layer. The laminated coating, including the silver coating, preferably extends outwardly of the notches on the surface of the ceramic plate immediately surrounding the notches. The terminal mounts are supported in ele tronic equipment and connecting wires and the leads of electrical components, such as resistors, capacitors, etc., are positioned in the notches, and touched With a soldering iron either with or without additional soft solder to secure such Wires together and in the notches.

The interior surfaces of the notches in the ceramic plates have heretofore been coated with the silver paint by an operation requiring considerable hand work. An element in the form of a comb having a tooth for each of the notches to be coated has been pivoted adjacent a bath of the paint so that the comb teeth could be dippedinto the paint and then elevated above the surface of the paint. A coating of the paint is thus produced on the comb teeth. One of the ceramic plates has then been manually applied to the comb elements so that the notches therein each fit around one of the comb teeth. The ceramic plate has been worked back and forth along the comb teeth until a satisfactory coating has been adhered to the interior surfaces of each notch. This has been an inefficient and a time consuming operation adding materially to the cost of the terminal mounts.

In accordance with the present invention, the coating of the interior surface of the notches is accomplished by positioning in each notch a hollow coating member filled 3,121,020 Patented Feb. 11, 1964 ice with silver paint and having walls made of a thin foraminous material and then forcing a plunger into such member to'discharge the paint through the foraminous walls into contact with the interior surfaces of the notch. Such member constitutes a cylinder for receiving the plunger. The foraminous Walls of the cylinder member may be made of gauze or of thin metal pierced with a pinrality of small holes. Such cylinder member may be of a size which fits Within the notch with the walls of the cylinder member spaced a slight distance from the interior surfaces of the notch to provide clearance for the coating of silver paint.

The cylinder member is filled with the ceramic paint, preferably by withdrawing the plunger from the interior of the cylinder member While both are submerged in a bath of silver paint. The cylinder member is then removed from the bath and positioned in the notch referred to above. The same or a different plunger is then inserted into the cylinder member to force the paint outwardly through the apertures in the foraminous walls of the cylinder member and into contact with the interior surfaces of the notch. Preferably, the cylinder member has sufiicient volume that some of the paint flows onto the surfaces of the plate immediately surrounding the notch and upon Withdrawal of the cylinder member, a substantially uniform coating of the paint is left in the interior surfaces of the notch and on the surfaces immediately surrounding the notch. The cylinder member can then be returned to the bath for another load of silver paint for coating another notch.

A plurality of cylinder members may be mounted upon a common carrier member for immersion and removal from the bath and may be spaced upon such carrier member so as to register with a plurality of notches in a notched member or alternatively, a single notch may be coated with a single cylinder member for each coating op eration. In any event, the process and apparatus specifically disclosed in this application lends itself to rapid coating of one or more notches in the edges of plate members with a coating liquid and also lends itself to coating selected portions of other articles having angularly disposed or otherwise difficultly accessible surfaces which cannot be coated by prior art methods, such as silk screen or analogous coating operations applicable to flat surfaces of considerable area.

It is therefore an object of the present invention to provide an improved method and apparatus for coating portions of the surfaces of articles with a coating liquid.

Another object of the invention is to provide a method and apparatus of coating difficultly accessible surfaces of an article in which an adherent liquid is forced outwardly through foraminous Walls of a cylinder member by a plunger while the cylinder member is positioned adjacent such surface. 3

Another object of the invention is to provide a method and apparatus for coating the interior surfaces of a notch in the edge of a plate member in which a charge of coating liquid is introduced into the interior of a hollow coating member having foraminous Walls and a plunger is employed to force the liquid through the Walls of the coating member into contact with the interior surfaces of the notch.

Other objects and advantages of the invention Will appear in the following description of a specific embodiment of the invention given in connection with the attached drawing of which: FIG. 1 is a perspective view of a terminal mount strip having a coating of silver paint on the interior surfaces of the notches and on the surfaces around the edges of such notches;

FIG. 2 is a diagrammatic vertical section through a 3 notch coating apparatus in accordance with the present invention for coating the interior surfaces of notches in terminal mount strips;

FIG. 3 is a diagrammatic plan view of the apparatus of FIG. 2 with the strip holding drum broken away to show the notch coating mechanism;

FIG. 4 is a diagrammatic view on an enlarged scale illustrating a step of the process in which silver paint is drawn into the interior of a foraminous cylinder member immersed in a bath of such paint;

FIG. 5 is a view similar to FIG. 4 showing the filled cylinder member partly removed from the bath of liquid and with the plunger in the same relative position to the cylinder member as in FIG. 4;

FIG. 6 is a view similar to FIG. 5 showing the plunger further withdrawn from the cylinder member and the cylinder member inserted into a notch in the edge of a plate member;

FIG. 7 is a view similar to FIG. 6 showing the plunger inserted into the cylinder member to force the silver paint through the walls of the cylinder member to coat the interior surfaces of the notch;

FIG. 8 is a view similar to FIG. 7 showing the cylinder member still in position in the notch but with the plunger withdrawn from the cylinder member;

FIG. 9 is a view diagrammatically showing the coated notch and also showing the cylinder member again immersed in the bath of liquid and with the plunger again inserted into the cylinder member ready to be withdrawn to the position of FIG. 4;

FIG. 10 is a diagrammatic plan view showing the top of one of the cylinder members; and

FIG. 11 is a fragmentary diagrammatic view showing a modified apparatus by which notches in the edges of a disc member may have their interior surfaces coated.

Referring more particularly to the drawings, a glazed ceramic strip 10 is shown in FIG. 1 as having a plurality of notches 12 therein. Each of the notches has its interior surfaces coated with a layer 14 of silver paint or ceramic silver and such coating extends a short distance from the notches 12 along the surfaces of the strip 19 immediately surrounding the notches.

FIGS. 4 to 9 of the drawing illustrate the steps of the process by which the coating 14 of silver paint is applied to the interior surfaces of the notches and adjacent surfaces of the strip. In FIG. 4, a hollow rectangular cylinder member 16 having foraminous walls is shown immersed in a bath 20 of the silver paint and a cooperating plunger 18 is shown as being withdrawn from the interior of the foraminous portion of the cylinder member 16 so as to draw a charge of the liquid into the cylinder member through its foraminous walls. The cylinder member has its lower end inserted in and secured in an aperture in a cylinder carrier 22 and the plunger 13 has its lower end secured to a plunger carrier 24. F or applying a coating to a strip having a plurality of notches therein, each cylinder carrier and plunger carrier supports a plurality of properly spaced cylinder members and plungers, respectively, as shown in FIGS. 2 and 3.

After a cylinder member has been filled with the liquid drawn into the cylinder member through its foraminous walls by withdrawal of the associated plunger 18 from the cylinder member, the cylinder member 16 with its charge of silver paint and also the plunger 18 are elevated above the surface of the bath 20 to the position of FIG. 5, while the plunger member 18 and cylinder member 16 are maintained in substantially the same position relative to each other. The cylinder member is thereby positioned to be inserted into a notch 12 in the plate 10 and the plate 10 is supported in position so that each notch 12 therein receives a cylinder member 16 with the foraminous walls of such member spaced slightly from the interior surfaces of the notch 12. It is preferred to further withdraw the plunger from each cylinder member 16 before inserting such cylinder member into the notch 12 in order to draw at least some of the silver paint adhering to the outer surface of the cylinder member and indicated at 25 in FIG. 5 into the interior of the cylinder member. This prevents an excessive amount of such paint being scraped from the cylinder member during insertion into the notch 12, which paint would otherwise xcessively pile up at the entrance to the notch.

The preferred manner of further withdrawing the plunger 13 from the cylinder member 16 is to slow down or even stop the plunger momentarily just after the plunger and cylinder member have reached the position of FIG. 5. The plunger and cylinder member thus are brought to the position relative to each other shown in FIG. 6 before the cylinder member is inserted into the notch 12. The plunger and cylinder member are then again moved together so that the upper end of the cylinder member is inserted into the notch 12. The cylinder member and plunger then occupy the position shown in FIG. 6. A preferred operation is to provide an amount of clearance in the space between the walls of the cylinder member and notch such that a small amount of the paint on the outside of the cylinder member is scraped therefrom and is collected on the edge surfaces of theplate immediately adjacent the notch. The amount thus collected can be controlled by the amount of the clearance just referred to and by the distance the plunger is Withdrawn from the cylinder member just after the plunger and cylinder member reach the positions of FIG. 5.

When a cylinder member 16 and associated plunger 18 have reached the position shown in FIG. 6, the cylinder member 16 is stopped and motion of the plunger 18 is continued upwardly so that the plunger 18 is inserted into the cylinder member 16 to force the charge of liquid silver paint in the cylinder member 16 outwardly through the foraminous walls thereof into contact with the interior surfaces of a notch 12. The resulting position of a plunger and cylinder member is shown in FIG. 7. The silver paint forms the coating 14 which not only covers all of the interior surfaces of the notch 12 but also covers a portion of the surfaces of the strip 10 immediately surrounding the notch 12, as is shown in FIG. 9.

The plunger 18 is then withdrawn from the cylinder member to the position shown in FIG. 8 while the cylinder member remains in position in the notch 12. This withdraws a portion of the silver paint in the notch back into the interior of the cylinder member and breaks any coherent contacts between the paint on the walls of the notch and the interior of the cylinder member. The cylinder member 16 can then be withdrawn from the notch 12 without excessive dragging of the silver paint out of such notch. The cylinder and plunger are again lowered below the surface of the liquid 29' during which movement the plunger is again inserted into the cylinder member so that the cylinder member and plunger occupy the position shown in FIG. 9. The plunger 18 is' then again withdrawn from the cylinder member 16 t0 the position shown in FIG. 4 to draw a fresh charge of silver paint into the cylinder member. A new strip 10 having one or more notches 12 therein is then placed in position to be coated and the process repeated.

An apparatus for supporting the strips during the coating operation and for moving the cylinder and plunger 1 carrier to carry out the process described with reference to FIGS. 4 to 9, is shown diagrammatically in FIGS. 2 and 3. Such apparatus may include a support drum 28 having grooves 3t} therein, each of which may receive a strip 10 with the notches 12 therein directed outwardly of the drum. The drum 28 may be indexed by any SlllF.

able mechanism so as to successively position the strips 11) directly above a plurality of cylinder members 16 positioned upon the cylinder carrier 22. Thus the drum i 2% may be mounted on a shaft 32 journaled in suitable bearings 34 supported on a frame 35 which also supports a container 33 for the bath 211 of silver paint. The drum 28 may be driven through a chain drive 46 so as to be intermittently indexed to any one of eight positions from a speed reducer and indexing mechanism 42 shown as being mounted upon the base frame 36. The speed reducer and indexing mechanism 42 may be driven by a suitable electric motor 44. The strips may be inserted in the upper portions of the drum 28 and removed from such drum after they have passed through the lowermost coating station by a manual operation or by any suitable strip inserting and removing mechanism.

The cylinder carrier '22 is secured to the ends of a pair of arms 46 supported on slides 48 mounted for vertical reciprocation in guides 50 and vertically reciprocated by cams 52 engaging rollers 53 and secured to a cam shaft 54 journaled in bearings 56 supported on the lower portion of the frame 36 and driven from the motor 44 through the speed reducer 42 and a chain drive 57. The plunger carrier 24 is secured to the ends of a pair of spaced arms 58 supported on slides 60 also mounted for vertical reciprocation in the guides 50 and vertically reciprocated by cams 62 secured to the shaft 54 and engaging rollers 64 on the lower ends of the slides 60.

The individual cylinder members 16 may be fabricated in any desired manner. One way is to fold a strip of gauze or a thin sheet of perforated metal around a form having approximately the shape of the plunger to be employed with the cylinder member. Thus a form having rectangular lateral cross section may be employed for making the rectangular cylinder elements shown in the drawings. The edges of the strip may be folded around the short sides of the form and pressed into the position indicated at 65 in FIG. 10 and soldered in position.

It will be apparent that the apparatus shown in FIGS. 2 and 3 carries out the steps of the process illustrated in FIGS. 4 to 9 inclusive. In FIG. 2, the cylinder members 16 and plungers 18 are shown in a position corresponding to that shown in FIG. 6. The cylinder members have been filled with silver paint by withdrawal of the plungers 18 while beneath the surface of the liquid in the container, and the plunger 18 has been further withdrawn from the cylinder member above the surface of such liqiud. The cylinder members have then been inserted in the notches in the lowermost ceramic strip 10. The cams 62 are in a position such that continued rotation of such cams in a clockwise direction in FIG. 2 will actuate the slides 60 to raise the plunger carrier 24 and plungers 18 carried thereby. This inserts the plungers 18 into the cylinder members 16 and results in the position of the parts illustrated in FIG. 7. The coating 14 shown in FIGS. 7, 8 and 9 is thus applied to the interior surfaces of a notch 12 and the exterior surfaces of the strip 10 immediately surrounding such notch as shown in FIG. 9. Continued rotation of the cams 52 and 62 in a clockwise direction in FIG. 2 causes the plungers 18 to be withdrawn from cylinder members 16 and then causes the cylinder members and plungers to move downwardly together to withdraw the cylinder members 16 from the notches and immerse the cylinder members 16 and plungers 18 in the bath. During such movement the plungers 18 are again inserted into the cylinder members 16. The position of the parts resulting from this operation is illustrated in FIG. 9. Further rotation of the cams 52 and 62 maintains the carrier 22 for the cylinder members and the associated cylinder members 16 stationary while the plungers 18 are withdrawn from the cylinder members, the resulting positions of the cylinder members and plungers being illustrated in FIG. 4. During movement of the plungers 18 from the position shown in FIG. 9 to that shown in FIG. 4, silver paint is drawn into the cylinder members 16 through the foraminous walls thereof. Thereafter continued rotation of the cams 52 and 62 carries the cylinder members 16 and plungers 18 through the position shown in FIG. 5 to the position shown in FIGS. 2 and 6, which is the same position illustrated in FIG. 2. During the time the cylinders and plunger members are immersed in the bath 20, the drum 28 is indexed one step to position a new ceramic strip 10 to have the surfaces associated with its notches coated as described above, and such operation is continuously repeated.

After the surfaces of the notches in the ceramic strips have thus been coated, the coatings are dried to remove solvent from the silver paint and the strips are then fired at a temperature suiiicient to burn out the organic binder or vehicle of the silver paint and melt the silver without fusing the ceramic strip or glaze thereon. The result is a thin adherent layer of silver on the surfaces coated by the paint and thereafter the notched edge of the ceramic strip is dipped in soft solder and removed therefrom to leave a coating of soft solder on the coating of silver. This results in a laminated coating of silver and soft solder on the interior surfaces of the notches and on the surfaces immediately surrounding the notches.

A modified operation is illustrated diagrammatically in FIG. 11 in which the surfaces associated with notches 66 in the peripheries of annular members 68 of glazed ceramic material are coated with silver paint in a manner analogous to that described above. A plurality of such members 68' may be mounted upon a mandrel 70 which is indexed in a manner similar to the drum 28 of FIG. 2 to successively bring the various notches 66 into registry with cylinder members 16 of the same type described above. The cylinder members are oriented at right angles in a horizontal plane to the orientation shown in FIGS. 0. and 3, and are all carried by a cylinder carrier member 72. A plurality of plungers 18 are carried by a plunger carrier 76 and aligned with the cylinder members 16. The cylinder carrier 72 may be secured to a pair of arms 46, such as those shown in FIG. 2, and the plunger carrier 76 may 'be secured to a pair of arms 58, such as those also shown in FIG. 2. The structure and operation of the remainder of the coating machine may be entirely similar to that shown in FIGS. 2 and 3. Thus the mandrel 70 carrying the annular members 68 will be indexed for a number of coating operations corresponding to the number of notches in the annular member. The mandrel will then be removed and another mandrel 70 having additional annular members to be subjected to the coating operation substituted therefor.

While the invention has been described specifically in connection with coating the interior of notches in the edges of plate members with ceramic silver paint, it will be apparent that the invention has utility wherever it is desired to coat portions of an article with an adherent liquid, particularly where the surfaces to be coated are angularly disposed or are of non planar contour or are otherwise difiicultly accessible. Thus the coating cylinder or cylinders can have outer surfaces conforming to the surfaces to be coated. Also means other than that shown can be employed to supply the coating liquid to the interior of the coating cylinder. In general, the amount of coating liquid introduced into a coating cylinder will be greater than that required for the coating operation and the amount delivered through the toraminous wall of the cylinder will be metered or regulated by the extent of movement of the plunger in the cylinder.

-I claim:

1. The method of coating a selected portion of a surface of an article having an indentation in said portion with a coating liquid which comp-rises moving relative to each other said article and a hollow coating member having a forarninous wall shaped to conform to said portion including said indentation to position said foraminous wall adjacent to but spaced from said surface portion, said coating member containing a charge of said liquid, thereafter moving a plunger member and said coating member relative to each other to move said plunger member into said coating member to force the liquid in said coating member outwardly through said foraminous wall into contact with said surface portion, moving said plunger out of said coating member to reduce the adhesion of the coating member to the coating of said liquid produced on said surface portion, and moving said coating member and said article relative to each other to move said foraminous wall away from said surface portion to leave said coating of said liquid on said surface portion.

2. The method of coating the interior surfaces of a notch in a notched member with a coating liquid which comprises moving relative to each other said notched member and a hollow coating member insertable into said notch and having foraminous walls shaped to conform to said notch to position said coating member in said notch with said foraminous walls adjacent to but spaced from said surfaces, forcing coating liquid from the interior of said coating member outwardly through said foraminous walls into contact with said interior surfaces including the bottom surface of said notch, and moving said coating member and said notched member relative to each other to remove said coating member from said notch to leave a coating of said liquid on said interior surfaces.

3. The method of coating the interior surfaces of a notch in a notched member with a coating liquid which comprises movin-g relative to each other said notched member and a hollow coating member insertable into said notch and having foraminous walls with exterior surfaces shaped to conform to said notch and providing clearance relative to said interior surfaces to position said coating member in said notch with said foraminous walls adjacent to but spaced from said interior surfaces, said coating member containing a charge of said liquid, forcing said charge of liquid in said coating member outwardly through said formainous walls into contact with said interior surfaces including the bottom surface of said notch, and moving said coating member and said notched member relative to each other to remove said coating member from said notch to leave a coating of said liquid on said interior surf-aces.

4. The method of coating the interior surfaces of a notch in a notched member including a bottom surface and a pair of side surfaces with a coating liquid which comprises moving relative to each other said notched member and a hollow coating member insertable into said notch and having foraminous side and end walls with exterior surfaces shaped to conform to said notch and providing clearance relative to said interior surfaces to position said coating member in said notch so that said eX- terior surfaces are spaced from said interior surfaces, said coating member containing a charge of said liquid, thereafter moving a plunger member and said coating member relative to each other to move said plunger member into said coating member to force the liquid in said coating member outwardly through said fo-raminous walls into contact with said interior surfaces including said bottom surface, and moving said coating member and said notched member relative to each other to remove said coating member from said notch to leave a coating of said liquid on said interior surfaces.

5. The method of coating the interior surfaces of a notch in a notched member with a coating liquid, which comprises the steps of moving relative to each other a plunger member and a cylinder member insertable into said notch and having foraminous walls with exterior surfaces shaped to conform to said notch and providing clearance with said interior surfaces while said cylinder member is immersed in a bath of said liquid to withdraw said plunger member from said cylinder member and fill said cylinder member with said liquid through said walls, moving said cylinder member and said bath relative to each other to withdraw said cylinder member from said bath, moving said notched member and said cylinder member relative to each other to position said cylinder member within said notch so that said foraminous walls are spaced from the interior surfaces of said notch, moving said plunger member and said cylinder member relative to each other while maintaining said cylinder mem- V ber in said notch to move the last mentioned plunger member into said cylinder member and force the liquid in said cylinder member outwardly through said foraminous walls into contact with said interior surfaces, moving said cylinder member and said notched member relative to each other to remove said cylinder member from said notch to leave a coating of said liquid on said interior surfaces, moving said cylinder member and said bath relative to each other to again immerse said cylinder member in said bath and repeating said steps to coat the interior surfaces of another notch.

6. The method of coating the interior surfaces of a notch in a notched member with a coating liquid, which comprises the steps of withdrawing a plunger member from the interior or" a cylinder member insertable into said notch and having foraminous walls with exterior surfaces shaped to conform to said notch providing clearance with said interior surfaces while said cylinder member is immersed in a bath of said liquid to fill said cylin der member with said liquid through said walls, removing said cylinder member from said bath, moving said cylinder member to position said cylinder member within said notch so that said foraminous walls are spaced from the interior surfaces of said notch, moving said plunger member into said cylinder member while maintaining said cylinder member in said notch to force the liq lid in said cylinder member outwardly through said foraminous walls into contact with said interior Walls, moving said cylinder member to remove said cylinder member from said notch to leave a coat ng of said liquid on said interior surf-aces, moving said cylinder member to again immerse said cylinder member in said bath and repeating said steps to coat the interior surfaces of another notch.

7. The method of coating the interior surfaces of a U- shaped notch with a viscous adherent liquid which comprises the steps of immersing in a bath of said liquid a cylinder member having foraminous walls with exterior surfaces conforming to the interior surfaces of said notch including the bottom thereof and providing clearance relative to said interior surfaces and containing a plunger, withdrawing said plunger from said cylinder member while said cylinder member is immersed in said bath to draw a charge of said liquid into the interior of said cylinder through said walls, removing said cylinder member and said plunger from said bath while said plunger and cylinder member are maintained stationary with respect to each other, inserting said cylinder member into said notch so that said foraminous walls are spaced from the interior surfaces of said notch, thereafter moving said plunger into said cylinder member to force said charge of liquid in said cylinder member outwardly through said walls into contact with said interior surfaces, removing said cylinder member containing said plunger from said notch to leave a coating of said liquid on said surfaces and repeating said steps to coat the interior surfaces of an other notch.

8. Apparatus for coating the interior surfaces of a notch in a notched member with a coating liquid which apparatus comprises, a hollow rectangular coating member insertable into said notch having foraminous side and end walls shaped to conform to said interior surfaces of said notch and means for positioning said walls in spaced relationship to said interior surfaces and for forcing a measured amount of said liquid from the interior of said coating member through said foraminous walls into concoating member is positioned in said notch, means for V filling said coating member with said liquid, and means operable while said coating member is positioned in said notch to force the liquid in said coating member through said foraminous walls into contact with said interior surfaces.

10. Apparatus for coating the interior surfaces of a notch in a notched member with a coating liquid, which apparatus comprises, a hollow rectangular cylinder member insertable into said notch having foraminous side and end walls with exterior surfaces conforming to said interior surfaces and providing clearance with said interior surfaces when said cylinder member is positioned in said notch, means for filling said cylinder member with said liquid, and plunger means movable relative to said cylh der member into the interior of said cylinder member While said cylinder member is positioned in said notch to force the liquid in said cylinder member through said foraminous walls into contact with said interior surfaces.

11. Apparatus for coating the interior surfaces of a notch in a notched member with a liquid material, said apparatus comprising a container for a bath of said material, a support for said member adjacent said bath, a hollow cylinder member insertable into said notch and having foraminous walls with exterior surfaces shaped to conform to said notch surfaces and providing clearance with said notch surfaces when said cylinder member is positioned within said notch, means for moving said cylinder member and said bath relative to each other to immerse said cylinder member in said bath, a plunger, means to move said cylinder member and said plunger relative to each other while said cylinder member is immersed in said bath to draw liquid material into said cylinder member, means to move said cylinder member and said bath relative to each other and to move said cylinder member and said support relative to each other to remove said cylinder member from said bath and position said cyl'mder member in said notch, and means to move said cylinder and said plunger relative to each other while said cylinder member is positioned in said notch to force the liquid material in said cylinder member outwardly through said walls into contact with said interior notch surfaces, and means to move said cylinder member and said support relative to each other to remove said cylinder member from said notch to leave a coating of said liquid material on said interior notch surfaces.

12. Apparatus for coating the interior surfaces of a notch in a notched member with a liquid material, comprising a container for a bath of said material, a support for said member adjacent said bath, a cylinder member insertable into said notch having foraminous walls with exterior surfaces shaped to conform with said notch surfaces and providing clearance with said notch surfaces When said cylinder member is positioned within said notch, means for moving said cylinder member into said bath to immerse said cylinder member in said bath, a plunger, means to withdraw said plunger from said cylinder member while said cylinder member is immersed in said bath to draw liquid material into said cylinder, means to move said cylinder member out of said bath and toward said support to position said cylinder member in said notch, and means to move said plunger into said cylinder member While said cylinder member is positioned in said notch to force the liquid material in said cylinder member outwardly through said walls into contact with said interior notch surfaces, and means to remove said cylinder member from said notch to leave a coating of said liquid material on said interior notch surfaces.

13. Apparatus for coating the interior surfaces of a notch in a notched member with a liquid material, said apparatus comprising a coating member insertable into said notch, said coating member including a strip of foraminous material folded about a line medial of its length and having its adjacent edges secured together to provide a pocket having foraminous side and end walls, said walls being spaced from each other to provide a hollow interior for receiving said liquid and for receiving a plunger, a plunger insertable into said hollow interior of said coating member, and means to move said plunger into said coating member While said coating member is positioned in said notch to force the liquid material in said coating member through said walls into contact with said interior surfaces.

14. A method of coating the interior surfaces of a groove in a grooved member with a liquid, which comprises the steps of:

inserting a hollow coating member into said groove,

said coating member having a foraminous wall por tion shaped to conform to said groove and being positioned with said foraminous wall portion adjacent to but spaced from all of the interior surfaces of said groove; and

transmitting coating liquid from within said coating member outwardly through said foraminous wall portion into contact with all of said interior surfaces including the bottom of said groove.

15. Apparatus for coating the interior surfaces of a groove in a grooved member with a liquid, comprising:

a hollow coating member having foraminous side and end Walls conforming to the interior surfaces of said groove and adapted to be positioned within said groove with said Walls spaced from said interior surfaces; and

means for passing coating liquid from the interior of said coating member outwardly through said foraminous Walls into contact with said interior surfaces of said groove.

References Cited in the file of this patent UNITED STATES PATENTS 419,457 Knowlton Jan. 14, 1890 802,278 Frey Oct. 17, 1905 1,004,768 Furber Oct. 3, 1911 1,387,641 Dobberteen Aug. 16, 1921 1,521,184 Holton Dec. 30, 1924 2,159,128 Brophy May 23, 1939 2,611,336 Sachs Sept. 23, 1952 2,677,835 Kamborian May 11, 1954 2,698,449 Rafferty Ian. 4, 1955 2,877,480 Warren Mar. 17, 1959 

14. A METHOD OF COATING THE INTERIOR SURFACES OF A GROOVE IN A GROOVED MEMBER WITH A LIQUID, WHICH COMPRISES THE STEPS OF: INSERTING A HOLLOW COATING MEMBER INTO SAID GROOVE, SAID COATING MEMBER HAVING A FORAMINOUS WALL PORTION SHAPED TO CONFORM TO SAID GROOVE AND BEING POSITIONED WITH SAID FORAMINOUS WALL PORTION ADJACENT TO BUT SPACED FROM ALL OF THE INTERIOR SURFACES OF SAID GROOVE; AND TRANSMITTING COATING LIQUID FROM WITHIN SAID COATING MEMBER OUTWARDLY THROUGH SAID FORAMINOUS WALL PORTION INTO CONTACT WITH ALL OF SAID INTERIOR SURFACES INCLUDING THE BOTTOM OF SAID GROOVE. 